In recent years, there has been deep concern by the general public and municapalities over the pollution of the environment from the discharge of pollution containing gases into the atmosphere from incinerators and the like. Consequently, technology of incinerators has increased in recent years wherein now certain types of controlled air incinerators are able to meet Federal, State and local regulations regarding pollutants in the discharging flue gases. Such an incinerator has been developed wherein burnable waste material may be automatically fed to a combustion chamber, burnt therein and removed therefrom without effecting the burning conditions therein and whereby the flue gases issuing therefrom have a minimum or no pollutants therein. This type of controlled air incinerator is disclosed in U.S. Pat. No. 3,855,950, issued Dec. 24, 1975 to Hughes et al and assigned to the common assignee of this application and for the purpose of this application, the disclosure in the aforementioned patent is incorporated herein by reference.
More recently, with the advent of the problems resulting from an energy crisis because of the shortage of petroleum products and natural gas, efforts are being made to conserve energy where ever possible. With regard to incinerators wherein the temperature of the flue gases is in the order of 1200.degree. to 2400.degree. F. or more, the energy provided by this temperature was completely wasted by early incinerator systems but due to recent awareness of the general energy crisis, efforts have now been made to utilize any energy which can be obtained from the high temperature hot flue gases. In this respect, incinerator systems have been proposed with the provision of a heat exchanger for heat recovery from in the stack system of incinerators, the heat being recovered to convert water into hot water or steam utilized for heating a building or providing a hot water distribution system in a building or for supplying steam for various purposes in plants such as hospitals, textile mills or the like. One such system for recovering energy from the hot flue gases of an incinerator is disclosed in U.S. Pat. No. 3,844,233, issued Oct. 29, 1974 to Fishback and assigned to the common assignee of this application. The subject matter of the disclosure of the Fishback patent is incorporated herein by reference.
One disadvantage in prior controlled air incinerators, as well as controlled air incinerators utilizing a heat recovery system for saving energy, is that the combustion chamber could not be made large enough to take care of waste material available or to supply heat over a long period of time to render such system economical for installation in large industrial plants. Such prior systems ordinarily required a number of smaller units, if the system was to be utilized as a twenty-four hour operation for supplying heat to a large building. Additionally, such prior combustion systems did not provide for complete combustion of all of the waste material fed to the combustion chamber, especially when the waste material was highly compacted as it entered the combustion chamber. The resultant charge of burning waste material was such that it would burn about the periphery of the charge and the tightly packed waste material in the center of the charge was starved from the oxygen of the combustion air resulting in incomplete combustion.